The present disclosure relates generally to high efficiency and mechanically durable solar cells. Specifically, the present disclosure relates to solar cells fabricated from boron nitride, and, in particular, boron nitride carbon alloys.
Most commercially available solar cells convert about 12% of incident sunlight energy into electricity. This relatively low conversion rate of incident sunlight to electricity (often referred to as “efficiency”) is a significant factor in the cost of renewable energy generated from solar cells.
One cause of the low efficiency of conventional solar cells is the relatively narrow band gap used in the semiconductor devices of conventional solar cells. That is, semiconductor materials generally used to fabricate commercial solar cells have band gaps from between 1.1 eV to 1.7 eV. For “single junction” solar cells, in which constituent p-n junctions use a single type of p material and a single type of n material for all p-n junctions in the solar cell, the band gap is narrow—on the order of several tenths of an electron volt (eV) centered around the band gap at the interface between the materials used to make the junction. This narrow range of energy in the band gap results in a narrow range of wavelengths present in the spectrum of sunlight that can be converted to electricity by the solar cell.
Further complicating this is that the spectrum of sunlight available for conversion at the Earth's surface is not continuous over a spectrum of wavelengths. Sunlight transmitted in the vacuum of space can be approximated as black body radiation, which includes a continuous range of wavelengths of light. Sunlight received at the Earth's surface, however, has interacted with components of the Earth's atmosphere. As a result, many wavelengths of light originally present in sunlight (i.e., when in the vacuum of space) are absorbed by components of the atmosphere before reaching the Earth's surface. This complicates the efficient conversion of sunlight into electricity using conventional solar cells because some solar cells may be configured to convert wavelengths of light to electricity that have been absorbed by the Earth's atmosphere prior to reaching the solar cell.
Multi junction solar cells that include a variety of band gaps in the constituent p-n junctions are configured to convert a wider range of wavelengths to electricity. However, the interfaces of p-n junctions of multi junction solar cells must be epitaxial, which substantially increases the cost of solar cell fabrication.